My mom wants to officiate

I agree with Anna.... You've tried to be tactful, but given the circumstances you've described, now you just need to shut this down and Anna has provided a good way to word it. Once you've told her, make it clear it's not up for discussion. Perhaps offer her the opportunity to give a toast at the rehearsal, if she feels strongly that she wants to say something. If things get out of hand with her emotions at the time, and she can't do that, no problem, no one will miss it, but she gets to plan on having her "moment." Good luck to you!

I'm sorry you are in this situation. It sounds like even if you wanted your mom to officiate, she wouldn't be able to do it. Weddings are crowds & she would for sure see your dad, it would be way worse from the officiant perspective. I would sit her down and say you want a stress free day, and don't want to give anyone a job so you already hired an officiant. Then tell her some other way she is involved, like getting ready with you, etc.

Ugh it's definitely a tough spot to be in but I agree with PPs that you are going to have to just flat out tell her no. Tell her that while you appreciate the offer you and FH would prefer your friend to do it. You've always imagined your wedding day with her as a guest of honor being able to watch you get married and that you don't want to give her a job to do on such a especial day - you want her to relax and enjoy herself.

My mom is a priest, and tbh, if she wasn’t my mom, I would want her in a heartbeat as I love her weddings! However, ever since I was little, she always told me she would not officiate my (or my sister’s) wedding because she wants to enjoy being “mom” and not working. She has changed her tune slightly now and has said that if I really want her to do it, she will, but I don’t want her to. I think it is important that we can both enjoy the day as her just being my mom. She is going to write a prayer for us, but other than that she isn’t involved in the ceremony.